Close proximity devices operate within a short range from a reader device. For example, radio-frequency identification (RFID) tags may be appended to various goods for wireless access with a reader device when in close proximity. As the RFID tags offer only relatively slow data transfer, there is ongoing development of faster technologies. For instance, RF memory tags are developed in which radio-frequency identification tags are accessed with very high data rates in comparison to the presently used RFID tags. These RF memory tags may be powered by a continuous wave radio signal at one set powering radio frequency (for example 13.56 MHz or 900 MHz) while data transfer is carried out using simple on-off keying on another set communication radio frequency.
The RF memory tags may be designed to operate over short distances in order to enable data rates in range of 100 times compared to those of the present RFID tags. As with the present RFID tags, the RF memory tags each may have a unique identifier for addressing by a reader device. On powering by the powering radio frequency signal, each of the RF memory tags gets a random timing with relation to the reader, due to the structure of the RF memory tags and due to varying radio propagation delay. Thanks to the short range, it is unlikely that two RF memory tags would get common timing with relation to the reader and thus there is no collision control to prevent RF memory tags from interfering each other's discovery by the reader.